1909.] Yeast-juice from Hexose and Phosphate. 537 



power than a solution of fructose having the same optical activity. The 

 ratio of the rotation to the reduction was always lower than that for pure 

 fructose, and varied from 1\36 to 2 - 78. This might be accounted for by the 

 presence of glucose or mannose, and experiments were made to ascertain if 

 these sugars were present ; in no case, however, could either be detected. 

 The insoluble hydrazone of mannose was not obtained with phenylhydrazine, 

 nor was a hydrazone formed when the syrup was treated with methyl- 

 phenylhydrazine in the manner described by Neuberg* for the separation of 

 glucose or mannose from fructose. They were also examined for glucose by 

 the method by which Lobry de Bruyn and van Ekensteinf detected glucose 

 in the mixtures obtained by the action of alkalis on fructose or mannose. 

 This consisted in removing most of the fructose by precipitating as calcium 

 fructosate or by extracting successively with alcohol, ethyl acetate, ether, and 

 acetone, and identifying glucose in the residue either by converting into 

 a-methyl glucoside by means of methyl alcoholic hydrochloric acid, or by 

 oxidising with dilute nitric acid and precipitating the acid potassium salt of 

 the saccharic acid formed. Neither of these compounds could be obtained 

 from the syrups under examination. 



In order to ascertain whether these low ratios were due to the action of 

 the phosphoric acid on the fructose after it was set free, a mixture of these 

 compounds in the same relative proportions as would be contained in 

 hexosephosphoric acid was boiled for some hours, and the phosphoric acid 

 then removed by means of barium hydrate and alcohol in a similar manner 

 to that described for the hydrolysed acid. The results of two experiments 

 are given in Table IX. 



Table IX. 



Time, 



in hours. 



— Eotation in 4 dm. tube. 



Reduction per 100 c.c. 



Eatio. 



(1) 







7-424 



1 -927 



3 -87 



10 



3 -832 



1 -082 



3-54 





15 



2 -580 



0-791 



3-26 



(2) 







0-711 



0-188 



3 -78 



10 



4-250 



1 -276 



3 -33 



In both these experiments the solutions became very dark coloured and 



a considerable quantity of fructose had been destroyed. It will be observed 



that in both cases the ratio became less on boiling, but the lowest value 



obtained was much higher than the numbers found for the product from 



hexosephosphoric acid. It is possible that the fructose as it is being formed 



* ' Ber.,' 1902, vol. 35, p. 959. 



t 'Eec. Trav.'Chim.,' 1895, vol. 14, p. 156. 



